CN108343497A - A kind of diesel vehicle SCR system ageing failure rapid diagnosis system and method - Google Patents

Abstract

The present invention provides a diesel vehicle SCR system aging failure rapid diagnosis system and method, by installing a data acquisition terminal on the OBD diagnostic interface of the diesel vehicle, real-time acquisition of the actual running speed of the diesel vehicle, diesel engine operating state parameters, _NOx concentration and other signals , the collected data information is uploaded to the cloud monitoring platform in real time through GPRS technology, and a diagnostic calculation model is designed in the cloud monitoring platform to monitor and quickly diagnose the aging and failure of the SCR system of diesel vehicles in real time, and realize remote online diagnosis of SCR of diesel vehicles A function of whether the system is functioning properly. The method of the present invention can effectively monitor the working condition of the SCR system of a diesel vehicle in real time and diagnose the aging and failure online, can supervise and maintain diesel vehicles more efficiently, improves the environmental protection ability of the whole society, and actively promotes the development of automobiles. The upgrading of relevant products will play a positive role in promoting the overall improvement of the automobile industry.

Description

A fast diagnosis system and method for aging failure of diesel vehicle SCR system

technical field

The invention belongs to the technical field of on-line diagnosis of the aging failure of the SCR system of a diesel vehicle, and in particular relates to a fast diagnosis system and method for the aging failure of the SCR system of a diesel vehicle.

Background technique

At present, mobile source pollutant emissions such as motor vehicles in the transportation field in my country have become a major problem in my country's environmental governance. As of the end of 2016, the number of motor vehicles in the country reached 295 million. Motor vehicle exhaust emissions have become the main source of air pollution in China, and are an important cause of ozone pollution and PM _2.5 . Nitrogen oxides NO _X are primary pollutants formed by ozone . According to the data of the "China Motor Vehicle Environmental Management Annual Report" (2017) issued by the Ministry of Environmental Protection, in 2016 China's motor vehicle NO _X emissions were 5.778 million tons.

In order to reduce _NOx emissions from diesel vehicles, heavy-duty diesel vehicles in the IV and V emission stages in China usually adopt SCR technology to meet the requirements of _NOx emission limits. However, during the use of SCR, there are generally situations such as SCR system signal failure or aging failure. Although all countries have formulated corresponding emission standards to conduct regular inspections on diesel vehicles, these traditional inspections are non-real-time inspections. The car owners leave opportunities for cheating, which is not conducive to timely discovery of high-emission vehicles with aging and invalid SCR systems, which brings hidden dangers to the social living environment and people's health.

On-Board Diagnostic (OBD) is a real-time monitoring and diagnostic system to ensure the normal operation of the vehicle emission control system. At present, the research is generally on the diagnosis technology and diagnosis method of diesel engine exhaust purification system components, but there is a lack of reliable and effective diagnosis technology and diagnosis method for the diagnosis of whether the purifier is working normally.

The present invention is mainly aimed at the relevant regulations in the regulations HJ437-2008 "Technical Requirements for Compression Ignition Type, Gas Fuel Ignition Type Engines for Vehicles and Automotive On-Board Diagnostic System (OBD)", utilizes the developed data acquisition terminal based on OBD, and connects to the OBD The data acquisition device of the interface transmits the vehicle data collected in real time to the cloud monitoring platform on the network. After precise algorithm and diagnosis in the cloud monitoring platform, it can be determined whether the SCR system of the diesel vehicle has signal failure or aging failure. A remote monitoring and rapid diagnosis method for the aging failure of the SCR system of the heavy-duty diesel engine facing the National IV and National V stages is proposed.

Contents of the invention

In view of this, the present invention aims to propose a rapid diagnosis system for the aging and failure of the SCR system of a diesel vehicle, so as to realize the remote monitoring and rapid diagnosis of the aging and failure of the SCR system of the heavy-duty diesel engine in China IV and China V stages.

In order to achieve the above object, technical solution of the present invention is achieved in that way:

A diesel vehicle SCR system aging failure rapid diagnosis system, including a data acquisition terminal and a cloud monitoring platform;

The data acquisition terminal is connected to the OBD diagnostic interface of the diesel vehicle for real-time collection including but not limited to parameter data generated during the actual operation of the diesel vehicle;

The data acquisition terminal transmits the collected signal to the cloud monitoring platform through the GPRS network;

The cloud monitoring platform is equipped with a diagnostic calculation model, which is used to calculate and analyze the data sent by the data acquisition terminal, and realize remote monitoring of the working state of the diesel vehicle SCR system and aging failure diagnosis; the diagnostic calculation model includes a _NOx sensor Signal authenticity diagnosis module, emission calculation and analysis module, diagnosis module, and result output module.

Further, the data collected by the data collection terminal includes but not limited to the actual running speed of the diesel vehicle, operating state parameters of the diesel engine, and _NOx concentration signal.

Further, the _NOx sensor signal authenticity diagnosis module is used for self-diagnosis of circuit connection faults, including short circuit faults, open circuit faults, whether the sensor power supply voltage is within a reasonable range, and whether the _NOx signal exceeds the maximum credible _NOx signal. value.

Further, the emission calculation and analysis module is used to receive data information from the diesel vehicle data acquisition terminal, and perform NO _X specific power emission calculation.

Further, the diagnosis module is used for diagnosing the working conditions of the SCR system according to the results output from the _NOx sensor signal authenticity diagnosis module and the emission calculation and analysis module.

Further, the result output module is used for real-time result output, information prompt and alarm of the diagnosis result of the diagnosis module.

Compared with the prior art, the aging and failure rapid diagnosis system of a diesel vehicle SCR system according to the present invention has the following advantages:

The invention performs data monitoring and diagnosis through the CAN line signal of the diesel vehicle remotely collected by the OBD, and can effectively monitor the working condition of the SCR system of the diesel vehicle in real time and diagnose aging failure online. The invention can not only supervise and maintain diesel vehicles more efficiently, improve the environmental protection ability of the whole society, but also actively promote the upgrading of automobile-related products, which has a positive role in promoting the overall improvement of the automobile industry level.

Another object of the present invention is to propose a rapid diagnosis method for the aging failure of the SCR system of a diesel vehicle, so as to realize the remote monitoring and rapid diagnosis of the aging failure of the SCR system of the heavy-duty diesel engine in the National IV and National V stages.

In order to achieve the above object, technical solution of the present invention is achieved in that way:

A method for quickly diagnosing aging failure of a diesel vehicle SCR system, specifically comprising the following steps:

(1) Use the data acquisition terminal to collect diesel engine speed, torque percentage, intake air mass flow, and NO _X concentration signals, and the collected data are transmitted to the cloud monitoring platform at a frequency of 1 Hz;

(2) The _NOx sensor signal authenticity diagnosis model of the cloud monitoring platform performs self-diagnosis on circuit connection faults;

(3) The emission calculation and analysis module of the cloud monitoring platform calculates the specific power emission of _NOx for short trips in the travel chain according to the data collected by the data collection terminal, and obtains the specific power emission value of _NOx for each short trip;

(4) The cloud monitoring platform uses the diagnostic module to diagnose based on the exceeding limit of the NO _X specific power emission limit;

(5) The cloud monitoring platform uses the result output module to output the diagnosis results in real time, and carry out information prompts and alarms.

Further, the calculation formula of the step (3) is as follows:

Among them, P _e is effective power, kW,

M _e is the measured effective torque, reference torque × torque percentage;

n, speed, r/min;

Exhaust mass flow rate (kg/h) = intake mass flow rate × 1.3 Formula 2

Among them, 1.3 is the empirical coefficient for the conversion of the mass flow rate of the intake and exhaust of the diesel engine;

NO _X emission mass (kg/h) = [(exhaust mass flow rate/29) _× NO _X concentration value] × 46 formula 3

29 is air molar mass; 46 is NO _X molar mass;

NO _X specific emission (g/kW·h)=(NO _X emission mass (kg/h)×1000)/P _e formula 4.

Further, the vehicle emission results are judged with reference to the limit value of the merit-based window method, the data collected by the data collection terminal is transmitted to the cloud monitoring platform, and the calculation is carried out according to the _NOx specific power calculation model to determine the judgment limit for the aging failure of the SCR system value standard.

The method for quickly diagnosing aging and failure of the SCR system of a diesel vehicle described in the present invention has the same beneficial effects as the above-mentioned system for rapidly diagnosing the aging and failure of the SCR system of a diesel vehicle, and will not be repeated here.

Description of drawings

The drawings constituting a part of the present invention are used to provide a further understanding of the present invention, and the schematic embodiments and descriptions of the present invention are used to explain the present invention, and do not constitute an improper limitation of the present invention. In the attached picture:

Fig. 1 is the diesel vehicle described in the embodiment of the present invention based on OBD data acquisition connection and signal transmission and diagnosis flow schematic diagram;

Fig. 2 is the diagnosis process of the _NOx sensor circuit connection-related failure described in the embodiment of the present invention;

Fig. 3 is a schematic diagram of a short-stroke segment in a certain travel chain according to an embodiment of the present invention;

Fig. 4 is a schematic diagram of the NO _x specific power emission value of each short stroke in a certain travel chain described in an embodiment of the present invention;

Fig. 5 is the schematic diagram of the discharge result of the normal SCR system of the national IV car described in the embodiment of the present invention;

Fig. 6 is a schematic diagram of the emission results of the normal SCR system of the national V vehicle described in the embodiment of the present invention;

Fig. 7 is a schematic diagram of the aging and failure emission results of the national IV vehicle SCR system described in the embodiment of the present invention;

Fig. 8 is a schematic diagram of the aging and failure emission results of the national V vehicle SCR system described in the embodiment of the present invention.

Detailed ways

It should be noted that, in the case of no conflict, the embodiments of the present invention and the features in the embodiments can be combined with each other.

In describing the present invention, it should be understood that the terms "center", "longitudinal", "transverse", "upper", "lower", "front", "rear", "left", "right", " The orientations or positional relationships indicated by "vertical", "horizontal", "top", "bottom", "inner" and "outer" are based on the orientations or positional relationships shown in the drawings, and are only for the convenience of describing the present invention and Simplified descriptions, rather than indicating or implying that the device or element referred to must have a particular orientation, be constructed and operate in a particular orientation, and thus should not be construed as limiting the invention. In addition, the terms "first", "second", etc. are used for descriptive purposes only, and should not be understood as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, a feature defined as "first", "second", etc. may expressly or implicitly include one or more of that feature. In the description of the present invention, unless otherwise specified, "plurality" means two or more.

In the description of the present invention, it should be noted that unless otherwise specified and limited, the terms "installation", "connection" and "connection" should be understood in a broad sense, for example, it can be a fixed connection or a detachable connection. Connected, or integrally connected; it can be mechanically connected or electrically connected; it can be directly connected or indirectly connected through an intermediary, and it can be the internal communication of two components. Those of ordinary skill in the art can understand the specific meanings of the above terms in the present invention based on specific situations.

The present invention will be described in detail below with reference to the accompanying drawings and examples.

The invention provides an OBD remote on-line monitoring based on a diesel vehicle SCR system aging failure rapid diagnosis system and method, belonging to the diesel vehicle SCR system aging failure on-line diagnosis technology. By installing a data acquisition terminal on the OBD diagnostic interface of a diesel vehicle, real-time collection of signals such as the actual running speed of the diesel vehicle, diesel engine operating state parameters, and NO _X concentration, the collected data information is uploaded to the cloud monitoring platform in real time through GPRS technology, and monitored in the cloud A diagnostic calculation model is designed in the platform to monitor and quickly diagnose the aging and failure of the SCR system of diesel vehicles in real time, and realize the function of remote online diagnosis of whether the SCR system of diesel vehicles is working normally.

As shown in Figure 1, the diagnostic system mainly includes diesel vehicles, OBD diagnostic interface, data acquisition terminal, data signal, cloud monitoring platform, _NOx sensor signal authenticity diagnostic module, emission calculation and analysis module, diagnostic module, and result output module. The data acquisition terminal is connected to the OBD diagnostic interface of the diesel vehicle, and collects the CAN line signal of the diesel vehicle, including the diesel engine speed, torque percentage, intake air mass flow, NO _X concentration and other signals. The collected data is transmitted to the cloud monitoring platform at a frequency of 1 Hz. The cloud monitoring platform is equipped with a NO _X sensor signal authenticity diagnosis module, an emission calculation and analysis module, a diagnosis module, and a result output module to realize data collection, storage, analysis and processing, diagnosis, alarm, etc. Function. The data acquisition terminal, with GPS function, can collect, record, and transmit the vehicle's running speed, engine speed, torque percentage, intake air flow, NO _X concentration and other information in the CAN line, and transmit it through the SIM card installed in the terminal To the cloud monitoring platform; the cloud monitoring platform can realize functions such as receiving data sent by the data collection terminal, data calculation and analysis, calculation model diagnosis and analysis, status alarm, etc., and has a visual UI interface.

1. The _NOx sensor signal authenticity diagnosis module performs self-diagnosis on circuit connection faults. Based on the CAN bus information collected by the OBD diagnostic interface, it is judged whether the _NOx sensor has a circuit connection fault. The routine faults include short-circuit faults, open circuit faults, whether the sensor power supply voltage is within a reasonable range, and whether the _NOx signal exceeds the maximum reliability of _NOx . value (refer to the measurement range of the _NOx sensor 0 to 1500×10 ^-6 ). Diagnosis process of _NOx sensor circuit connection-related faults is shown in Fig. 2.

2. Based on the vehicle speed, diesel engine speed, torque percentage, _NOx concentration and other signals collected by the data acquisition terminal as the input of the _NOx sensor signal authenticity diagnosis model, the specific power emission calculation of _NOx in short trips in the travel chain is performed, according to The monitoring limit designed by the monitoring department judges the emission of NO _X and diagnoses the working condition of the SCR system.

3. The _NOx sensor signal authenticity diagnosis module takes the travel chain as a judging event, and performs short-stroke motion short-segment cutting on the travel chain. The short-stroke cutting method constructs a motion from the starting point of idle speed to the starting point of the next idle speed. Fragments, as shown in Figure 3.

4. The _NOx specific power emission calculation module of the short stroke segment is calculated based on the following formula.

Among them, P _e is effective power, kW,

M _e is the measured effective torque, reference torque × torque percentage; n, speed, r/min;

Exhaust mass flow rate (kg/h) = intake mass flow rate × 1.3 Formula 2

Among them, 1.3 is the empirical coefficient for the conversion of the mass flow rate of the intake and exhaust of the diesel engine;

NO _X emission mass (kg/h) = [(exhaust mass flow rate/29) _× NO _X concentration value] × 46 formula 3

29 is air molar mass; 46 is NO _X molar mass;

NO _X specific emission (g/kW·h)=(NO _X emission mass (kg/h)×1000)/P _e formula 4.

Calculate the _NOx specific power emission of each short stroke according to the method of _NOx specific power emission value described in the present invention, take a national five diesel vehicle as an example, the _NOx of each short stroke in a certain travel chain of this car The specific power emission values are shown in Fig. 4.

5. The present invention diagnoses the aging failure of the SCR system based on the exceeding limit of the NO _X specific power emission limit.

(6) The present invention proposes a method for determining the NO _X specific power emission limit, referring to DB11/965-2013 "Heavy-duty Vehicle Exhaust Pollutant Emission Limit and Test Method (On-board Method)", respectively for three National IV and three A new National V heavy-duty diesel vehicle is used for on-board emission testing. At the same time as the on-board testing, a data collection terminal is installed for data collection. The vehicle emission results are judged with reference to the limit value of the merit-based window method, and the data collected by the data collection terminal is transmitted to the cloud monitoring platform and calculated according to the NO _X specific power calculation model. See Table 1 for the passing rate of the on-board test of the SCR system of a new car under normal working conditions, and the calculation model of specific power of NO _X based on OBD data collection (the specific power emission of cumulative frequency 90% (see Fig. 5 and Fig. 6), g/kW·h). The pass rate of different test methods under the normal condition of the SCR system. All the vehicles to be tested have passed the on-board test, _and the data collected synchronously through the data acquisition terminal is _calculated through the NO _X specific power calculation model. The average NO _X specific power emission value of the vehicle is 10.7g/kW h, multiplied by the deterioration coefficient 1.2 (preliminarily set at 1.2 in the present invention), and the NO _X specific power emission limit value of the national IV vehicle judging aging failure is 13.0g/kW h; the average NO _X specific power emission of national V diesel vehicles is 9.0g/kWh, multiplied by the deterioration coefficient 1.2, the specific power emission value is 11.0g/kWh. Through the method proposed by the invention, the judgment limit standard for the aging failure of the SCR system of the national IV and national V vehicles is determined.

Table 1

(7) After the present invention proposes the _NOx specific power emission limit method for judging the aging failure of the SCR system, the rationality of the established emission limit is verified by simulating the aging failure of the SCR system by artificially manufacturing _NOx emissions exceeding the standard. After mixing urea with water (simulating the aging failure of the SCR system), the on-board emission test and synchronous data collection terminal collection are carried out. The test results are shown in Table 2. The pass rates of different test methods for the aging failure of the SCR system all failed the on-board test, and Based on OBD data collection, the pass rate of 90% specific power emission of NO _X calculation model in normal state is in the range of 45% to 72%. The feasibility of the method for judging the aging failure of the SCR system based on the limit value of the NOX specific power emission of the travel chain proposed by the invention.

Table 2

(8) The diagnosis module diagnoses the working conditions of the SCR system according to the results output from the _NOx sensor signal authenticity diagnosis module and the emission calculation and analysis module.

(9) The result output module performs real-time result output, information prompt and alarm etc. of the diagnosis result of the diagnosis module.

The above descriptions are only preferred embodiments of the present invention, and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included in the scope of the present invention. within the scope of protection.

Claims (9)

1. A diesel vehicle SCR system aging failure rapid diagnosis system is characterized in that: it includes a data acquisition terminal and a cloud monitoring platform; The data acquisition terminal is connected to the OBD diagnostic interface of the diesel vehicle for real-time collection including but not limited to parameter data generated during the actual operation of the diesel vehicle; The data acquisition terminal transmits the collected signal to the cloud monitoring platform through the GPRS network; The cloud monitoring platform is equipped with a diagnostic calculation model, which is used to calculate and analyze the data sent by the data acquisition terminal, and realize remote monitoring of the working state of the diesel vehicle SCR system and aging failure diagnosis; the diagnostic calculation model includes a _NOx sensor Signal authenticity diagnosis module, emission calculation and analysis module, diagnosis module, and result output module. 2. A kind of diesel vehicle SCR system aging failure quick diagnosis system according to claim 1, it is characterized in that: the data collected by the data acquisition terminal includes but not limited to the actual running speed of the diesel vehicle, diesel engine operating state parameters, NO _X concentration signal. 3. A kind of diesel vehicle SCR system aging failure quick diagnosis system according to claim 1, is characterized in that: described _NOx sensor signal authenticity diagnosis module is used for self-diagnosis to circuit connection fault, comprises short circuit fault, open circuit Fault, whether the sensor power supply voltage is within a reasonable range, whether the NO _X signal exceeds the maximum credible value of NO _X. 4. A kind of diesel vehicle SCR system aging failure fast diagnosis system according to claim 1, is characterized in that: described emission calculation and analysis module is used for receiving the data information of diesel vehicle data acquisition terminal, carries out NO _X specific power emission calculation . 5. a kind of diesel vehicle SCR system aging failure rapid diagnosis system according to claim 1, is characterized in that: described diagnosis module is used for according to the result output of _NOx sensor signal authenticity diagnosis module, emission calculation and analysis module, to Diagnose the working condition of the SCR system. 6. A diesel vehicle SCR system aging failure rapid diagnosis system according to claim 1, characterized in that: the result output module is used for real-time result output, information prompt and alarm of the diagnosis result of the diagnosis module. 7. A method for quickly diagnosing aging and failure of a diesel vehicle SCR system according to the preceding claim, characterized in that it specifically comprises the following steps: (1) Use the data acquisition terminal to collect diesel engine speed, torque percentage, intake air mass flow, and NO _X concentration signals, and the collected data are transmitted to the cloud monitoring platform at a frequency of 1 Hz; (2) The _NOx sensor signal authenticity diagnosis model of the cloud monitoring platform performs self-diagnosis on circuit connection faults; (3) The emission calculation and analysis module of the cloud monitoring platform calculates the specific power emission of _NOx for short trips in the travel chain according to the data collected by the data collection terminal, and obtains the specific power emission value of _NOx for each short trip; (4) The cloud monitoring platform uses the diagnostic module to diagnose based on the exceeding limit of the NO _X specific power emission limit; (5) The cloud monitoring platform uses the result output module to output the diagnosis results in real time, and carry out information prompts and alarms. 8. A method for quickly diagnosing aging and failure of a diesel vehicle SCR system according to claim 7, characterized in that: the calculation formula of the step (3) is as follows: Among them, P _e is effective power, kW, M _e is the measured effective torque, reference torque × torque percentage; n, speed, r/min; Exhaust mass flow rate (kg/h) = intake mass flow rate × 1.3 Formula 2 Among them, 1.3 is the empirical coefficient for the conversion of the mass flow rate of the intake and exhaust of the diesel engine; NO _X emission mass (kg/h) = [(exhaust mass flow rate/29) _× NO _X concentration value] × 46 formula 3 29 is air molar mass; 46 is NO _X molar mass; NO _X specific emission (g/kW·h)=(NO _X emission mass (kg/h)×1000)/P _e formula 4. 9. A method for quickly diagnosing aging and failure of a diesel vehicle SCR system according to claim 7, characterized in that: the vehicle emission results are judged with reference to the limit value of the merit-based window method, and the data collected by the data acquisition terminal is transmitted to the The cloud monitoring platform calculates according to the NO _X specific power calculation model to determine the judgment limit standard for the aging failure of the SCR system.